01 - Combine bread flour, sourdough starter, water, and salt in a large bowl. Mix until a shaggy dough forms. Cover and let rest for 30 minutes.
02 - Perform 2 to 3 sets of stretch and folds over the next 1.5 hours, allowing the dough to rest for 30 minutes between each set. After the final fold, cover and refrigerate the dough overnight for 8 to 12 hours.
03 - Generously oil a 9x13-inch baking pan. Transfer the chilled dough to the pan, gently stretching it to fit. Cover and let rise at room temperature for 2 to 3 hours until very puffy.
04 - Beat cream cheese, sugar, egg yolk, vanilla extract, and lemon zest in a medium bowl until smooth and creamy. Set aside until ready to use.
05 - Toss fresh raspberries with granulated sugar and lemon juice in a small bowl. Set aside to allow the berries to release their juices.
06 - Preheat oven to 425°F.
07 - Dimple the risen focaccia dough with oiled fingers. Dollop the cheesecake mixture evenly across the surface, then gently swirl with a knife or spatula. Scatter the sugared raspberries and their juices over the dough.
08 - Drizzle additional olive oil over the surface. Bake for 25 to 30 minutes until golden brown, set in the center, and the edges are crisp.
09 - Allow the focaccia to cool for at least 30 minutes before slicing. Serve warm or at room temperature for the best texture and flavor.